package priv.pront.code.mati.national.practice;

import java.util.Scanner;

/**
 * @Author: Pronting
 * @Description:
 * @DateTime: 2023/12/1 12:39
 **/
public class B3638_T1三角形面积 {


    static int[][] arr = new int[3][2];
     public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        for (int i = 0; i < 3; i++) {
            arr[i][0] = scanner.nextInt();
            arr[i][1] = scanner.nextInt();
        }
        double a = Math.sqrt(Math.pow(arr[0][1] - arr[1][1], 2) + Math.pow(arr[0][0] - arr[1][0], 2));
        double b = Math.sqrt(Math.pow(arr[0][1] - arr[2][1], 2) + Math.pow(arr[0][0] - arr[2][0], 2));
        double c = Math.sqrt(Math.pow(arr[2][1] - arr[1][1], 2) + Math.pow(arr[2][0] - arr[1][0], 2));
        double s = 0.5 * (a + b + c);
        double p = Math.sqrt(s * (s - a) * (s - b) * (s - c));
        int ans = (int)Math.round(p);
         System.out.println(ans);
    }


}
